PDF(Pubmed)
Abstract：
Ubiquitin-specific protease 14 (USP14), one of the three major proteasome-associated deubiquitinating enzymes (DUBs), is known to be activated by the AKT-mediated phosphorylation at Ser432. Thereby, AKT can regulate global protein degradation by controlling the ubiquitin-proteasome system (UPS). However, the exact molecular mechanism of USP14 activation by AKT phosphorylation at the atomic level remains unknown. By performing the molecular dynamics (MD) simulation of the USP14 catalytic domain at three different states (inactive, active, and USP14-ubiquitin complex), we characterized the change in structural dynamics by phosphorylation. We observed that the Ser432 phosphorylation induced substantial conformational changes of USP14 in the blocking loop (BL) region to fold it from an open loop into a β-sheet, which is critical for USP14 activation. Furthermore, phosphorylation also increased the frequency of critical hydrogen bonding and salt bridge interactions between USP14 and ubiquitin, which is essential for DUB activity. Structural dynamics insights from this study pinpoint the important local conformational landscape of USP14 by the phosphorylation event, which would be critical for understanding USP14-mediated proteasome regulation and designing future therapeutics.
摘要：
泛素特异性蛋白酶14（USP14），三种主要的蛋白酶体相关去泛素化酶（DUB）之一，已知在Ser432被AKT介导的磷酸化激活。因此，AKT可以通过控制泛素-蛋白酶体系统（UPS）来调节整体蛋白质降解。然而,AKT磷酸化在原子水平激活USP14的确切分子机制尚不清楚.通过在三种不同状态（非活性，活跃,和USP14-泛素复合物），我们通过磷酸化表征了结构动力学的变化。我们观察到Ser432磷酸化诱导了USP14在阻断环（BL）区域的实质性构象变化，将其从开环折叠成β折叠。这对USP14激活至关重要。此外，磷酸化还增加了USP14和泛素之间的临界氢键和盐桥相互作用的频率，这对于DUB活动至关重要。本研究的结构动力学见解通过磷酸化事件确定了USP14的重要局部构象景观，这对于理解USP14介导的蛋白酶体调节和设计未来的治疗方法至关重要。
